Exercise training, without weight loss, increases insulin sensitivity and postheparin plasma lipase activity in previously sedentary adults

OBJECTIVE - To determine the effects of exercise, without weight loss, on insulin sensitivity (S-1), postheparin plasma lipase activity (PHPL), intravenous fat clearance rate (K-2), and fasting lipids in sedentary adults. RESEARCH DESIGN AND METHODS - At baseline and after 6 months of walk training (intensity 45-55 or 65-75% heart rate reserve, frequency 3-4 or 5-7 days/week, duration 30 min/session), anthropometric indexes, S-1 PHPL, K-2, and fasting lipids were measured in 18 sedentary adults (12 women, 6 men; 51.9 +/- 5.8 years of age, BMI 28.9 +/- 4.6 kg/m(2)). RESULTS - Exercise increased S-1 (2.54 +/- 2.74 vs. 4.41 +/- 3.30 muU.ml(-1).min(-1), P < 0.005) and both lipoprotein lipase (LPL) (1,890 ± 1,380 vs. 4,926 ± 1,858 nEq free fatty acid [FFA].ml.(-1).h(-1)) and hepatic lipase (HL) activities (3,326 ± 1,605 vs. 4,636 ± 1,636 nEq FFA.ml(-1).h(-1)) (both P < 0.001), without altering BMI, waist circumference, K-2 or fasting lipids. Correlations between changes in LPL and the total:HDL cholesterol ratio (r = -0.54) and changes in the LPL:HL ratio and waist circumference (r = -0.50) were significant (P < 0.05). CONCLUSIONS - Exercise, without weight loss, increases S-1 and PHPL activity in previously sedentary adults, without changing K-2 or fasting lipid levels. Furthermore, increased LPL is associated with a decreased total:HDL ratio, and an increased LPL:HL ratio is associated with a decreased waist circumference. Therefore, even modest amounts of exercise in the absence of weight loss positively affect markers of glucose and fat metabolism in previously sedentary, middle-aged adults.